Directional differential pressure detector

ABSTRACT

Methods and apparatuses for indicating the presence of a directional differential pressure between separated adjacent spaces are provided. A differential pressure set point indicator may be configured to correlate multiple potential angles of inclination of an elongated conduit to respective threshold differential pressures between two spaces which generate net flow of fluid sufficient to cause a lightweight ball to move from one region of the conduit to an opposing region. The elongated conduit may be adjustable in length so as to accommodate installation of the device into walls of varying thickness. The device may include a sound attenuator that reduces noise upon impact of the ball with either end of the conduit. The device may also include a sealing material that is flexible yet firm enough to provide both a seal with the exterior surface of the conduit and support for the conduit when oriented in a tilted configuration.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application No.14/210,607, filed Mar. 14, 2014, entitled “DIRECTIONAL DIFFERENTIALPRESSURE DETECTOR,” which claims priority to U.S. ProvisionalApplication No. 61/791,703 filed Mar. 15, 2013, entitled “DIRECTIONALDIFFERENTIAL PRESSURE DETECTOR,” the contents of each of which areincorporated herein by reference in their entirety.

FIELD

Aspects of the present disclosure relate generally to methods andapparatuses for detecting the presence of a directional differentialpressure.

DISCUSSION OF RELATED ART

Various applications within hospitals, laboratories, pharmaceuticalfacilities, clean room facilities, etc., often require a particulardirection of air flow to be maintained, such as between neighboringrooms, compartments, corridors, ducts, or other spaces. The pressure ofa room relative to adjacent space(s) will determine the net direction ofair flow through an opening into or out of the room.

For example, a hospital operating room, containing a patient who isundergoing surgery, may be supplied with highly filtered air so as toachieve a positive pressure, i.e., so that more air flows out of theroom than into the room, thereby preventing dirty or infectious air fromentering the room and entering the patient's wound. This positivepressure is accomplished by supplying clean air to the operating room ata greater flow rate than the flow rate at which air is exhausted fromthe room. Such an arrangement, where the operating room has acomparatively higher pressure than its surroundings, prevents air whichmay contain bacteria or other undesirable airborne contaminants fromentering the operating room from the surrounding space(s).

Or, if a hospital patient is infected with an airborne communicablepathogen such as tuberculosis, the room may be kept under a negativepressure, i.e., the rate at which potentially contaminated air isexhausted from the room is greater than the rate at which air issupplied to the room and from the immediate surroundings. Such anegative pressure arrangement, where the room is under a comparativelylower pressure than its immediate surroundings, prevents air, which maycontain bacteria or other undesirable airborne contaminants, fromexiting the room and escaping into surrounding space(s).

The net differential pressure between rooms will cause air to flow fromone room to the other in the direction from a higher pressure to a lowerpressure. Depending on the application, the desired degree ofdifferential pressure to be maintained between rooms, compartments,corridors, etc. will vary. For example, it is likely that a room thatcontains a highly infectious or hazardous matter should be kept under agreater degree of negative pressure than a room that contains a toxinthat does not cause major concern.

Thus, it is often necessary for the general direction of air flowbetween compartments be closely monitored as well as the particularmagnitude of differential pressure causing the net air flow. Inaddition, it may be desired to change the magnitude of differentialpressure between rooms, for example, when the application of the roomhas changed.

SUMMARY

The inventor has appreciated that it would be beneficial to provide asimple detection system for fluid (e.g., air) flow that providesquantitative information regarding different degrees of differentialpressure that may exist between adjacent spaces (e.g., enclosed rooms,compartments, corridors, etc.) and the associated causal direction offluid flow between the spaces. As an example, the differential fluid(e.g., air) pressure between, e.g., two adjacent enclosed spaces A and Bseparated by a wall may be zero or more positive in space A than space Bor more positive in space B than space A, causing a potential of air toflow between the spaces from zero or in the direction from space A to Bor in the direction from space B to space A, respectively. The relativepressure between space A and B forms a differential pressure anddepending on which space is of higher pressure, the relative pressure isdirectional in nature, i.e., causes a fluid to flow in a direction froma higher pressure region towards a lower pressure region and therefore adirectional differential pressure exists.

Directional differential pressure detectors described herein may provideinformation that allows an observer to know immediately whether or notthe room, as compared with its immediate surroundings, exhibits aparticular direction of air flow, into or out of the room in response toa particular degree of negative or positive pressure difference, whichmay be required under set protocols for the room. Further, directionaldifferential pressure detectors of the present disclosure may provide anobserver not only with an indication that the direction of air flow fromone space to another is in the desired direction, but also may informthe observer with the approximate magnitude of pressure differencebetween the spaces.

In some embodiments disclosed herein, a detection system is readilyadjustable to account for changes in the use of the space. For example,when it is desired to change the direction of air flow and/or thedifferential pressure between spaces, differential pressure detectorsdiscussed herein may be adjusted in a simple manner so as to provide anindication of whether the direction and magnitude of differentialpressure between the spaces actually falls within the adjusted range.

A device for detecting a directional differential pressure betweenenclosed and neighboring spaces may include an elongated conduit that isarranged to extend through a wall connecting the spaces. The conduit mayhave openings at opposite ends that permit fluid (e.g., air) to flowbetween the otherwise enclosed spaces through the conduit in a directionthat corresponds with the existing differential pressure between thespaces. A movable element (e.g., a lightweight ball) may be disposedwithin a lumen of the conduit so as to be affected by directional airflow generated by the pressure differential. That is, in response to theexisting differential pressure between neighboring rooms, the resultingdirectional air flow may move the movable element from one region of theconduit to an opposite region (e.g., between two ends).

When the conduit is tilted at an angle with respect to a horizontalreference plane, one end of the conduit is positioned vertically lowerthan the opposite end. Absent net fluid flow through the conduit, themovable element falls by force of gravity to the lower end of theconduit. Though, given a sufficient amount of fluid flow through theconduit, from the lower end of the conduit towards the higher end (e.g.,due to a net pressure differential), the force of gravity on the movableelement may be overcome such that the movable element moves toward thehigher end of the conduit.

The device may include a differential pressure set point indicator thatresponds to the angle of inclination of the conduit with respect to ahorizontal plane. In particular, the differential pressure set pointindicator may be configured and calibrated (e.g., based on a givensize/weight of the movable element, parameters of the conduit, size ofthe openings at each end of the conduit) to correlate the angle ofinclination of the conduit to a threshold differential pressure betweenthe two spaces that is sufficient to cause the movable element withinthe conduit to move from one region (e.g., at a vertically lowerposition) of the conduit towards an opposite region (e.g., at avertically higher position). For example, the greater the degree of tiltof the conduit, the greater the differential pressure required togenerate sufficient fluid flow in the conduit to move the movableelement from a lower region towards a higher region.

In some embodiments, the elongated conduit is adjustable in length. Forexample, the conduit may have two separate telescoping components thatare slidable with respect to one another. Such adjustability in lengthmay accommodate installation of the device into walls of varyingthicknesses.

The movable element within the conduit may be contained by a stop neareach of the ends of the open ended conduit. When the movable elementimpacts either of the stops of the conduit, in some cases, a noticeablesound may be heard, largely depending on the relative compositions ofthe movable element and the stop(s) of the conduit. For instance, withthe conduit installed at an incline from the horizontal, when thedifferential pressure between spaces becomes equal (e.g., the doorbetween the room and an outside corridor is opened resulting in pressureequalization), the movable element may drop down from a higher verticalposition back to a lower vertical position within the conduit, and theimpact of the movable element with a lower end stop of the conduit mayproduce a sound. Such a sound may be irritating to those in closeproximity to the lower end of the conduit, particularly if repeatedfrequently. For example, hospital inpatients in an infectious isolationroom or laboratory mice in a vivarium, may be awakened during theirsleep cycle each time the staff enters and exits the room. Accordingly,the device may include a sound attenuator that is adapted to reducenoise upon impact of the movable element from one region of the conduitto an opposing region. In some embodiments, the sound attenuator may bea relatively soft energy absorbing material or include an energyabsorbing geometry provided as part of an end stop.

The device may further include a sealing material (e.g., gasket) placedin contact with the exterior surface of the conduit so as to provide aseal between the surface of the wall and the conduit when the device isinstalled. Accordingly, transfer of potentially contaminated air betweena space and the interior cavity of a hollow wall may be substantiallyprevented. As the conduit may be positioned at a particular angle ofinclination when installed, the sealing material may be flexible toprovide and maintain a seal as well as accommodate appropriateadjustment(s) in position of the conduit (e.g., from one angle ofincline to another). Yet, the sealing material may also be firm enoughto provide a suitable amount of support for the tilted conduit (e.g., tomaintain the position/orientation of the conduit).

In an embodiment, a device for detecting a directional differentialpressure between two spaces is provided. The device includes anelongated conduit arranged to extend through a wall separating a firstspace from a second space, the conduit having openings at opposite endsthat permit fluid flow through the conduit from the first space to thesecond space, the conduit arranged to be inclined with respect to ahorizontal reference plane such that a first region of the conduitassociated with the first space is vertically lower than a second,vertically higher region of the conduit that is associated with thesecond space; a movable element disposed within the conduit adapted tobe moved from the first, vertically lower region of the conduit to thesecond, higher region or from the second higher region to the firstvertically lower region, in response to a differential pressure betweenthe first and second spaces; and a differential pressure set pointindicator configured to correlate each of a plurality of angles ofinclination of the conduit with respect to the horizontal referenceplane to a respective threshold differential pressure between the firstand second spaces that is sufficient to cause the movable element tomove from the first, lower region of the conduit to the second, higherregion.

In another embodiment, a device for detecting a directional differentialpressure between two rooms is provided. The device includes an elongatedconduit arranged to extend through a wall separating the two spaces, theconduit having openings at opposite ends that permit fluid flow betweenthe two spaces through the conduit, the conduit being adjustable inlength; and a movable element disposed within the conduit adapted to bemoved from one region of the conduit toward an opposing region inresponse to the differential pressure.

In yet another embodiment, a device for detecting a directionaldifferential pressure between two rooms is provided. The device includesan elongated conduit arranged to extend through a wall separating thetwo spaces, the conduit having openings at opposite ends that permitfluid flow between the two spaces through the conduit; a movable elementdisposed within the conduit adapted to be moved from one region of theconduit toward an opposing region in response to the differentialpressure; and a sound attenuator adapted to reduce noise upon themovable element reaching one of the two conduit ends.

In another embodiment, a device for detecting a directional differentialpressure between two rooms is provided. The device includes an elongatedconduit arranged to extend through a wall separating the two spaces, theconduit having openings at opposite ends that permit fluid flow betweenthe two spaces through the conduit; a sealing material in contact withan exterior surface of the conduit and adapted to support the conduit inan installed orientation; and a movable element disposed within theconduit adapted to be moved from one region of the conduit toward anopposing region in response to the differential pressure.

In yet another embodiment, a method of installing a device for detectinga directional differential pressure between two spaces is provided. Themethod includes positioning an elongated conduit to extend through awall separating a first space from a second space, the conduit havingopenings at opposite ends that permit fluid flow through the conduitfrom the first space to the second space, the conduit arranged to beinclined with respect to a horizontal reference plane such that a firstregion of the conduit associated with the first space is verticallylower than a second, vertically higher region of the conduit that isassociated with the second space, wherein a movable element disposedwithin the conduit is adapted to be moved from the first, verticallylower region of the conduit to the second, higher region in response toa differential pressure between the first and second spaces; referringto a differential pressure set point indicator to determine a firstangle of inclination of the conduit with respect to a horizontalreference plane that corresponds to a first threshold differentialpressure between the first and second spaces that is sufficient to causethe movable element to move from the first, lower region of the conduitto the second, higher region; tilting the conduit to achieve thedetermined first angle of inclination of the conduit with respect to thehorizontal reference plane that corresponds to the first thresholddifferential pressure; referring to the differential pressure set pointindicator to determine a second angle of inclination of the conduit withrespect to the horizontal reference plane that corresponds to a secondthreshold differential pressure between the first and second spaces,different from the first threshold differential pressure, that issufficient to cause the movable element to move from the first, lowerregion of the conduit to the second, higher region; and tilting theconduit to achieve the determined second angle of inclination of theconduit with respect to the horizontal reference plane that correspondsto the second threshold differential pressure.

Advantages, novel features, and objects of the invention will becomeapparent from the following detailed description of the invention whenconsidered in conjunction with the accompanying drawings, which areschematic and which are not intended to be drawn to scale. For purposesof clarity, not every component is labeled in every figure, nor is everycomponent of each embodiment of the invention shown where illustrationis not necessary to allow those of ordinary skill in the art tounderstand the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are not intended to be drawn to scale. In thedrawings, each identical or nearly identical component that isillustrated in various figures is represented by a like numeral. Variousembodiments of the invention will now be described, by way of example,with reference to the accompanying drawings. The embodiments anddrawings shown are not intended to narrowly define the invention.

FIG. 1 is a cross-sectional view of a device subject to a differentialpressure in accordance with some embodiments;

FIG. 2 is a cross-sectional view of the device of FIG. 1 at a differentorientation;

FIG. 3 is a cross-sectional view of a device for detecting adifferential pressure in accordance with some embodiments;

FIG. 4 is a partial perspective view of the device of FIG. 3;

FIG. 5 is a partial cross-sectional view of another device for detectinga differential pressure in accordance with some embodiments;

FIG. 6 is a partial perspective view of the device of FIG. 5;

FIG. 7 is a partial cross-sectional view of a further device fordetecting a differential pressure in accordance with some embodiments;

FIG. 8 is a partial cross-sectional view of yet another device fordetecting a differential pressure in accordance with some embodiments;

FIG. 9 is a partial cross-sectional view of a different device fordetecting a differential pressure in accordance with some embodiments;

FIG. 10 is a partial cross-sectional view of another device fordetecting a differential pressure in accordance with some embodiments;

FIG. 11 is a partial cross-sectional view of a further device fordetecting a differential pressure in accordance with some embodiments;

FIG. 12 is a partial perspective view of a holder used with a device fordetecting a differential pressure in accordance with some embodiments;

FIG. 13 is a cross-sectional view of the holder used with the device ofFIG. 12;

FIG. 14 is a partial cross-sectional view of a sound attenuator usedwith a device for detecting a differential pressure in accordance withsome embodiments;

FIG. 15 is a partial exploded view of the sound attenuator used with thedevice for detecting a differential pressure of FIG. 14;

FIG. 16 is a partial cross-sectional view of another sound attenuatorused with a device for detecting a differential pressure in accordancewith some embodiments;

FIG. 17 is a partial cross-sectional view of yet another soundattenuator used with a device for detecting a differential pressure inaccordance with some embodiments;

FIG. 18A is a partial cross-sectional view of another sound attenuatorused with a device for detecting a differential pressure in accordancewith some embodiments;

FIG. 18B is a cross-sectional view of another sound attenuator inaccordance with some embodiments;

FIG. 19 is a cross-sectional view of a device for detecting adifferential pressure in accordance with some embodiments;

FIG. 20 is an exploded view of the device of FIG. 19;

FIG. 21 is a partial cross-sectional view of a support used with adevice for detecting a differential pressure in accordance with someembodiments;

FIG. 22 is a partial cross-sectional view of the support used with thedevice of FIG. 21 in a tilted orientation;

FIG. 23 is a cross-sectional view of another device for detecting adifferential pressure in accordance with some embodiments;

FIG. 24 is a perspective view of an adjustable portion of a device fordetecting a differential pressure in accordance with some embodiments;

FIG. 25 is a cross-sectional view of a different device for detecting adifferential pressure in accordance with some embodiments; and

FIG. 26 is a perspective view of another adjustable portion of a devicefor detecting a differential pressure in accordance with someembodiments.

DETAILED DESCRIPTION

The present disclosure relates to a device that provides an indicationof directional air flow and whether a particular degree of directionaldifferential pressure exists between spaces separated by a wall (e.g.,two neighboring rooms). In some embodiments, the device includes anelongated conduit with openings on opposite ends. A ball, or othermovable element, is disposed within a lumen of the conduit and may movefreely back and forth along the length of the conduit. Restraints or endstops located at opposite ends of the conduit may be used to contain theball within the conduit so that the ball does not exit from the conduit.The end stops may have openings that allow fluid (e.g., air, inert gas,liquid) to flow through the lumen of the conduit from one end to anopposite end.

The device may include a differential pressure set point indicatorassociated with the conduit and a movable element within the lumen ofthe conduit. The set point indicator may be configured to correlate theincline of the conduit with respect to the horizontal plane to arespective threshold directional differential pressure between the twoadjacent spaces sufficient to cause the movable element to move from alower region of the inclined conduit to a higher region. The directionaldifferential pressure set point indicator may include, for example, abubble vial, a rotating weighted pendulum pointer, or other componentsthat respond to the incline of the conduit and correlate to adirectional differential pressure set point. The differential pressureset point indicator may be appropriately calibrated such that themarkings on the differential pressure set point indicator correspond tospecific minimum values of directional positive and/or negativedifferential pressure that may exist between spaces separated by a wall(e.g., at ends of the conduit). Accordingly, the differential pressureset point indicator may provide an indication of what angle of conduitinclination corresponds to the directional threshold differentialpressure set point between the two separated spaces that results inmovement of the ball from a lower region of the conduit towards anopposing, higher region of the conduit.

In some embodiments, when installed, the conduit extends from one sideof a wall to the other side such that opposite ends of the conduitextend outwardly into neighboring spaces that are separated by the wall.In some embodiments, only one end of the conduit extends outwardly fromthe wall. Air is permitted to flow between the spaces through theconduit, from one end of the conduit to the opposite end. When theconduit is inclined, and there is little to no net differential pressurebetween the spaces to which opposite ends of the conduit extend, theforce of gravity acting on the ball causes the ball to move toward orremain at the lower end of the conduit.

In practice, the incline of the conduit is such that the lower end ofthe conduit is placed in the room desired to be of a higher pressurerelative to the adjacent communicating room via the conduit where thehigher end of the conduit resides. In this arrangement, the desireddirection of air flow caused by this pressure differential will be fromthe higher pressure room with the low end of the conduit towards thelower pressure room with the higher end of the conduit.

Depending upon the physical features of the conduit (e.g., lumendiameter, straightness/curvature, surface finish), physical features ofthe ball (e.g., diameter, weight, surface finish), degree of incline ofthe conduit, fluid properties of the media between compartments, orificesize at the end stops, and the directional differential pressure betweencompartments, the equilibrium position of the ball may be on either endof the conduit such that the ball can be seen from the appropriatespace. Though, in some cases, depending at least in part on how theincline of the conduit is set relative to the existing differentialpressure between spaces, the ball may remain stationary at anintermediate location with respect to the ends of the conduit.

As an example, for a hospital isolation room occupied by a patient withan infectious disease that is capable of airborne transmission, it maybe desirable to keep the room at a negative differential pressurerelative to one or more adjacent rooms, so as to substantially preventairborne transmission of the disease to an adjacent room. In such anarrangement, the room exhausts more air than is supplied within it andfrom the surroundings, to an extent that the negative pressure is of agreater magnitude than any adjacent space. Thus, the conduit should beinstalled such that the end of the conduit that extends inside theisolation room is at a higher position than the opposite end of theconduit that extends into a space immediately exterior to the isolationroom (e.g., a corridor, a compartment, duct, or another room).

When the net differential pressure between the isolation room and theoutside space is zero (e.g., a door between the room and the outsidespace is opened), the ball will fall to the lower end of the conduitsuch that an observer inside the isolation room would not be able toview the ball; it follows that an observer outside the isolation roomwould be able to see the ball. When the appropriate degree of negativepressure is applied to the room, the ball moves upwardly within theconduit through the wall and into the isolation room. That is, thedifference between the pressure of the isolation room and the pressurein the outside space on the opposite side of the wall causes an air flowrate through the conduit that is sufficient to move the ball upwardlywhere it can be viewed from inside the isolation room—thereby indicatingthat at least the appropriate direction of air flow and degree ofnegative pressure is applied to the room.

In the case of a room that is required to exhibit a positive pressure,so as to substantially prevent air to flow from a surrounding regioninto a room, the net flow of air is from the room itself to theimmediate surroundings. Accordingly, the conduit is installed such thatthe end of the conduit that extends inside the room is at a lowerposition than the opposite end of the conduit that extends into thesurrounding space exterior to the room. Thus, when a suitable amount ofpositive pressure is applied to the room, there is sufficientdirectional air flow through the conduit to move the ball upwardlywithin the conduit through the wall to the conduit end located in thesurrounding space.

It may be necessary to adjust the device for different minimumdifferential pressures that give rise to respective directions of airflow between the spaces. For example, it may be desired that a roomcontaining cyanide be at a higher negative differential pressure ascompared to a wood processing plant room containing airborne sawdust. Ifit is desired that the magnitude of the negative pressure differencebetween a room and the outside space be increased, the conduit may beadjusted to be inclined at a greater angle relative to a horizontalreference plane. Devices described herein may allow for simpleadjustment of the angle of the conduit relative to a horizontalreference plane, so as to provide a clear indication as to whether thenewly desired net differential pressure exists to cause a desireddirection of air flow between the separate spaces.

When installed, the conduit may be set at an appropriate angle ofinclination that corresponds to the desired threshold differentialpressure set point to cause a desired direction of air flow betweenseparate spaces. In some embodiments, the desired differential pressurebetween separate spaces to which the device may provide an indication ofthe appropriate degree of incline may be between 0.001 inch of H₂O and10 inches of H₂O (e.g., between 0.001 inch of H₂O and 1 inch of H₂O,between 0.001 inch of H₂O and 5 inch of H₂O, between 0.005 inches of H₂Oand 0.5 inches of H₂O, between 0.1 inch of H₂O and 0.5 inches of H₂O,between 0.01 inch of H₂O and 0.1 inches of H₂O, between 0.01 inch of H₂Oand 0.05 inches of H₂O, between 0.01 inch of H₂O and 0.03 inches of H₂O,between 0.005 inches of H₂O and 0.1 inch of H₂O, between 0.001 inch ofH₂O and 0.005 inches of H₂O, between 0.001 inch of H₂O and 0.003 inchesof H₂O, etc.), as measured by a standard water column barometer. It canbe appreciated that devices of the present disclosure may provide anindication of other differential pressures between adjacent spacesoutside of these ranges.

As discussed, a differential pressure set point indicator may beappropriately secured to the conduit so as to provide a correlationbetween the angle of inclination of the conduit with respect to ahorizontal reference plane that corresponds to the thresholddifferential pressure between spaces that is required to generatesufficient directional air flow through the conduit to move the ballfrom an end at a lower position to the opposite end at a higherposition.

As an example, if the desired differential pressure leading to air flowin a particular direction between compartments separated by a wall is0.02 inches of H₂O, then, given the components of the system (e.g.,ball, conduit, orifices), the conduit may be angled in such a mannerthat the force of gravity on the ball will be overcome by thedirectional air flow created by at least 0.02 inches of H₂O pressuredifference between the compartments. Thus, if the angle of inclinationof the conduit is set for a differential pressure of 0.02 inches of H₂Obetween compartments, and the differential pressure between thecompartments is actually 0.01 inches of H₂O, then the amount ofdirectional air flow generated by the only 0.01 inches of H₂Odifferential pressure in the direction from the lower end to the upperend of the conduit will be insufficient to overcome the force of gravityon the ball, due to the angle of incline of the conduit being too high(conduit is too steep). The same holds if the direction of air flowwithin the conduit is from the higher end towards the lower end.

As a result, the ball will remain at the lower end of the conduitbecause the directional threshold differential pressure in the directionof air flow from the lower end to the higher end has not been met.However, if the angle of inclination of the conduit is adjusted to beless (conduit is less steep) so as to correspond to a lower, 0.01 inchof H₂O differential pressure in the desired direction of air flowbetween compartments, from the lower end towards the higher end of theconduit, then the amount of directional air flow generated between roomswill be sufficient to overcome gravity and move the ball from the lowerend to the higher end of the conduit.

FIG. 1 depicts a device 100 for detecting whether a directionaldifferential pressure is present between two spaces separated by a wall50. The device 100 includes a conduit 110 (e.g., tube) which hasopenings at opposite ends.

The conduit 110 extends from one surface 52 of a wall 50 to the oppositesurface 54. In this embodiment, the surface 52 corresponds to a firstroom 10 and the surface 54 corresponds to a second room 20 on theopposite side of the wall. The conduit 110 extends between neighboringrooms 10, 20 at an angle θ with respect to a horizontal reference planeh.

A movable element, such as a ball 120 (e.g., a ping pong ball, otherspherical ball) or other suitable article, is contained by end stops 130(e.g., end caps) that allow fluid flow through the end stop within alumen of the conduit. The ball 120 has an outer diameter that is lessthan the inner diameter of the conduit 110. In some embodiments, theball is made of a lightweight material and moves freely along the lengthof the conduit 110 between opposite ends. Any other suitable movableelement may be used, for example, a slidable block, a cylindricallyshaped article, etc. In some embodiments, multiple movable elements maybe used by the device simultaneously.

Each end of the conduit may be fitted securely with restraints or endstops 130. The end stops 130 have respective openings 132 through whichfluid (e.g., air) may readily flow. The openings 132 have respectiveshapes and sizes that prevent the ball from falling out of the conduitwhen the ball moves toward and impacts the end stop 130. For example,the opening 132 may have a diameter that is smaller than the outerdiameter of the ball 120, keeping the ball retained within the lumen ofthe conduit.

The end stops 130 may be suitably secured as caps at the ends of theconduit 110, for example, by a friction fit, snap fit, or otherwise. Insome embodiments, the end stops 130 and the conduit 110 are transparentor translucent so that the ball 120, when present, can be readily seenby a person observing the device from either space 10, 20 on oppositesides of the wall 50 in which the device is installed. In some cases,the ball 120 is brightly colored so that the ball is easily noticeableto a person who is looking at the device.

The conduit 110 is attached to the wall by a series of wall flanges. Inparticular, FIG. 1 shows inner wall flanges 150 and outer wall flanges160, along with inner sealing materials 152 and outer sealing materials162. The flanges 150, 160 are appropriately positioned so as toaccommodate the desired angle of inclination of the conduit. The conduitis held by the outer sealing materials 162 at the desired angle ofinclination, described further below.

An inner sealing material 152 is disposed between an inner wall flange150 and the surface 52. The inner wall flange 150 and inner sealingmaterial 152 may be secured (e.g., attached, adhered, fastened) togetherto the wall surface 52. As such, the inner sealing material 152 mayprovide an appropriate seal, preventing unwanted air leakage betweenrooms 10, 20 via the wall cavity space, should such a cavity exist.Additionally, the inner wall flange 150 and inner sealing material 152have respective openings that are large enough through which the conduit110 may extend without contact.

Outer wall flange 160, in turn, is secured (e.g., attached, adhered,fastened) to the inner wall flange 150 with the outer sealing material162 being disposed between the flanges 150, 160. The outer wall flange160 and outer sealing material 162 have openings through which theconduit 110 may extend. The inner sealing material 162 provides anappropriate seal preventing unwanted air leakage between rooms 10, 20,or via a wall cavity space. However, in various embodiments, the openingof the outer sealing material 162 has a diameter that is less than theouter diameter of the conduit 110 so that an appropriate seal may beformed between the outer sealing material 162 and the conduit 110. Suchan arrangement further allows the conduit 110 to be suitably supportedand held in a steady position when installed at an angle.

The wall flanges 150, 160 and sealing materials 152, 162 may be attachedto respective wall surfaces 52, 54 and to each other by any suitablemethod, for example, via an adhesive and/or fastener. The wall flanges150, 160 and sealing materials 152, 162 may be adjustable in position soas to accommodate variations in the angle of inclination θ of theconduit. In some embodiments, the inner wall flange 150 is attached tothe wall 50; however, the position of the outer wall flange 160 may beadjusted vertically with respect to the inner wall flange 150.Accordingly, the outer wall flanges 160 may be re-positioned to permitthe angle of the conduit to be appropriately altered.

The device 100, when installed, may be used to detect whether a desireddirectional differential pressure exists between the separate rooms 10,20. When the air pressure between the separate rooms 10, 20 is the same,there will be no net flow of fluid through the conduit from one room tothe other. Therefore, if the conduit is held at an angle of inclinationwith respect to the horizontal, due to gravity, the ball will fall downtoward the lower of the two end stops and rest against that stop.

However, when the air pressure between the rooms 10, 20 is not equal,there will be a net flow of fluid through the conduit from the room witha comparatively higher pressure toward the other room. In FIG. 1, thepressure within room 10 is higher than the pressure within room 20.Accordingly, air will flow in a direction from room 10 to room 20, asindicated by the arrows shown within the conduit. If the velocity of airflow from room 10 to room 20 meets a certain threshold, the air flowwill overcome the force of gravity on the ball causing the ball to movefrom the lower end of the conduit within room 10 towards the higher endof the conduit within room 20. Thus, for the embodiment of FIG. 1, whenthe ball moves from room 10, through the wall and into room 20, thedevice has indicated that the differential pressure between room 10 androom 20 has met a certain direction of air flow and a correspondingthreshold differential pressure causing the air flow through the conduitto travel in the direction from room 10 towards room 20.

In FIG. 2, there is no difference in pressure between the rooms 10, 20;hence, there is no net flow of air through the conduit. Accordingly,because the conduit remains at a slight angle of incline θ with respectto the horizontal h, the ball 120 rolls back to the lower end of theconduit, within room 10. In FIG. 1, the outer wall flange of room 10 ispositioned substantially lower than the outer wall flange of room 20.Accordingly, the conduit 110 is oriented according to a relatively steepangle. Though, in FIG. 2, the outer wall flange of room 10 is positionedto be in much closer alignment, vertically, with respect to the outerwall flange of room 20. Such positioning permits the conduit 110 to beoriented according to a much smaller angle of incline.

Other arrangements are possible. For example, a device (not shown in thefigures) may include an angled conduit where only one end extendsoutwardly from a wall, rather than two ends. Accordingly, depending onthe differential pressure between spaces, the ball may move between avertically higher region of the conduit and a vertically lower region ofthe conduit within the same room, or at least partially within a wallcavity.

In some embodiments, the device includes a differential pressure setpoint indicator that provides an indication (e.g., via a pointerreferencing various markings) of a minimum differential pressurethreshold that would cause the ball to move from a lower end regiontoward a higher opposite end region of the conduit. Markings of thedifferential pressure set point indicator may refer to actual units ofpressure indicating the directional threshold pressure differential setpoint between rooms. Markings may include alphanumeric values to which acorrelating table may be referred, to determine the correspondingdirectional threshold differential pressure set point. Or, in someembodiments, markings of the differential pressure set point indicatormay provide the actual inclination angle θ of the conduit with respectto a horizontal reference plane h, also to which a correlating table maybe referred, to determine the corresponding directional thresholddifferential pressure set point.

The differential pressure set point indicator may include a suitablepointer (e.g., an air bubble within a liquid, a ball within a fluid, atip pointer, a pendulum, a pivotally arranged member, a weighted member,etc.) and associated markings that, when referred to by the indicator,provide information regarding the angle of inclination of the conduitand corresponding directional threshold differential pressure set point.The markings may be calibrated such that steady alignment of theindicator with a particular region of the markings, resulting in aparticular angle of incline of the conduit, provides an indication to anobserver of the threshold differential pressure required to cause theball to move from a lower region to a higher region of the conduit.

It may be desirable for the device to provide assurance to an observerthat the direction of air flow and the associated differential pressurebetween separate spaces meets certain requirements. For example, thedifferential pressure requirement in a particular direction betweenneighboring rooms may be approximately 0.01 inch of H₂O, and thedifferential pressure set point indicator may have markings that, givena particular angle of incline of the conduit, correspond to thedifferent levels of differential pressure required to create sufficientair flow to cause the ball to move from a lower region (e.g., lower end)to a higher region (e.g., higher end) of the conduit. In this example,upon installation or adjustment of the device, the conduit may be set ata particular angle θ such that the pointer or bubble or ball of thedifferential pressure set point indicator comes into steady alignmentwith markings that correspond to a 0.01 inch of H₂O pressuredifferential. Accordingly, when the actual differential pressure betweenrooms is approximately 0.01 inch of H₂O or above, the directional airflow generated by the pressure difference will be sufficient to overcomethe force of gravity on the ball so as to move the ball toward thehigher end of the conduit.

When the differential pressure between rooms degrades (e.g., adoor/window is opened between rooms or the ventilation system airflowsdegrade from proper settings), then the directional differentialpressure between rooms may fall below approximately 0.01 inch of H₂O inthe direction from the lower end to the higher end of the conduit, andthe ball falls back to the lower end of the conduit, indicating to anobserver that the minimum directional differential pressure is notpresent. Or, when the directional differential pressure between therooms degrades due to other factors such as changes in the ventilationsystem and falls below 0.01 inch of H₂O in the direction from the lowerend towards the higher end of the conduit, then the force of gravityovercomes the force provided by the net air flow through the conduit andthe ball drops down to the lower end. In some embodiments, when thedirectional differential pressure between rooms inadvertently fallsbelow the desired directional threshold pressure differential, an alarmmay sound alerting the appropriate personnel that the direction of airflow or the directional threshold differential pressure requirements ofthe room are not met.

It may be desirable to have an adjustable range of differential pressureset points to accommodate different requirements between neighboringrooms, which may be accomplished by adjusting any of the associatedcharacteristics of the elements of the detector, e.g., the ball diameterand weight, the conduit lumen diameter, the end stop orifices, theincline of the conduit. For example, there may be a desired directionalair flow and associated threshold differential pressure of 0.05 inchesof H₂O, from a previous setting of 0.01 inch of H₂O. As a result, givenall other elements of the detector unchanged, the angle of incline ofthe conduit should be adjusted appropriately. If the conduit remains atthe angle corresponding to a differential pressure of 0.01 inch of H₂O,then an actual directional pressure difference between rooms of, forexample, 0.03 inches of H₂O in the same desired direction would give anobserver an erroneous indication that the directional thresholddifferential pressure between the rooms is at least 0.05 inches of H₂O.That is, for this example, the air flow generated by a differentialpressure of 0.03 inches of H₂O would cause the ball to move upwardwithin the conduit, despite the desired directional thresholddifferential pressure of 0.05 inches of H₂O.

Accordingly, the angle of incline of the conduit may be re-positioned ata different angle such that the pointer of the directional thresholddifferential pressure set point indicator comes into steady alignmentwith markings that correspond to a 0.05 inches of H₂O directionalthreshold pressure differential. Thus, only when the actual directionaldifferential pressure between rooms is 0.05 inches of H₂O or above, theair flow generated by the pressure difference will be sufficient toovercome the force of gravity on the ball so as to move the ball towardthe higher end of the conduit. If and when the differential pressurerequirement between neighboring rooms is to be changed yet again, thenthe angle of incline of the conduit may be further re-positioned to adifferent orientation that corresponds to the updated thresholddifferential pressure desired, according to the read out provided by thedifferential pressure set point indicator.

A number of different differential pressure set point indicatorssuitable for use with the device will now be presented.

FIGS. 3-4 show a device with an interchangeable bubble differentialpressure set point indicator 200. Each bubble differential pressure setpoint indicator has a vial containing a liquid and an associated bubble.When the bubble reaches a steady equilibrium alignment between the linedmarkings on the vial, the differential pressure set point indicator isconsidered to be level with respect to the horizontal.

As shown, any one of a series of bubble differential pressure set pointindicators 200 a, 200 b, 200 c may be appropriately secured to theconduit. Each bubble differential pressure set point indicator 200 has abase plate 214 constructed for appropriate attachment to a surface ofthe conduit. The bottom surface of each base plate 214 is sloped so thatwhen the respective differential pressure set point indicator isinstalled, the bubble will attain steady alignment between the linedmarkings when the conduit is set at a particular angle of incline. Thatis, the conduit will be positioned at an angle of incline that willallow the bubble of the differential pressure set point indicator tosteadily remain within the middle of the vial between the linedmarkings. Such an angle of incline will correspond to the desiredthreshold differential pressure between separate spaces that would causethe ball to be displaced from the lower end toward the higher oppositeend.

Referring to FIGS. 3-4, the currently installed differential pressureset point indicator 200 a corresponds to a threshold differentialpressure of 0.03 inches of H₂O. Accordingly, when the conduit isinstalled at the appropriate angle where the bubble of the differentialpressure set point indicator 200 a remains steadily at the middle of thevial, a directional differential pressure between rooms of 0.03 inchesof H₂O or greater in the direction that causes the air to flow in thedirection from the lower end to the higher end of the conduit and willgenerate enough air flow through the conduit to cause the ball to movefrom room 10 to room 20. Hence, if the directional differential pressurebetween rooms is less than 0.03 inches of H₂O in the direction from room10 to 20 or the directional differential pressure goes to zero orreverses, then the air flow through the conduit will be insufficient toovercome the force of gravity on the ball. In such a case, the ball willremain at the lower end of the conduit.

The differential pressure set point indicator 200 a may be appropriatelyreplaced with either of differential pressure set point indicators 200b, 200 c which, in this illustrative example, correspond to thresholdpressure differentials of 0.02 inches of H₂O and a 0.1 inch of H₂O,respectively. Thus, if the device is fitted with differential pressureset point indicator 200 b, when the conduit is installed at an anglesuch that the bubble pointer of the differential pressure set pointindicator 200 b remains steadily at the middle of the vial, adirectional differential pressure between rooms of 0.02 inches of H₂O orgreater in the direction from room 10 to 20 will cause the ball 120 tobe moved from room 10 to room 20. And if the differential pressurebetween rooms is less than 0.02 inches of H₂O in the direction from room10 to 20 or the directional differential pressure goes to zero orreverses, then the air flow through the conduit will be insufficient toovercome the force of gravity on the ball.

As shown in FIG. 3, the indicator senses the degree of incline. Thebottom surface of base plate 214 for attachment of differential pressureset point indicator 200 a (corresponding to a threshold differentialpressure of 0.03 inches of H₂O) to the conduit has a slope that isgreater than that of differential pressure set point indicator 200 bwhich, in turn, has a slope greater than that of differential pressureset point indicator 200 c. Accordingly, for the differential pressureset point indicators of FIGS. 3-4, a greater desired thresholddifferential pressure will require a greater degree of slope of theconduit

An embodiment of a device fitted with an adjustable bubble differentialpressure set point indicator is shown in FIGS. 5-6. Like other bubbledifferential pressure set point indicators, this differential pressureset point indicator includes a vial 210 with a liquid and associatedbubble pointer 212. The vial may be appropriately rotated about a pivot230 with a fastener (e.g., wing nut), capable of loosening and securingrotation of the vial about the pivot so that the vial points to markings220 that indicate corresponding threshold differential pressure valuesthat may be set between separate spaces which, in turn, correspond tothe appropriate angle of inclination of the differential pressure setpoint indicator 200 and, hence, the angle of the conduit 110 itself whenthe bubble pointer 212 is between the boundary lines 213. For instance,when it is desired for the device to be installed so as to extendthrough a wall and between rooms to indicate to an observer that adirectional differential pressure of at least 0.02 inches of H₂O ispresent, then, in the embodiment of FIGS. 5-6, the angular position ofthe vial on the pivot 230 is adjusted so that the vial 210 points to theparticular marking that references a pressure of 0.02 inches of H₂O inthe desired direction of air flow. The desired direction of airflow isdetermined by placing the low end of the conduit in the room of desiredhigher pressure relative to the other room where the high end of theconduit resides. Since the differential pressure set point indicator cansense both directions of the conduit incline, there may be similarsymmetric markings for the desired threshold differential pressure setpoint in each direction. Accordingly, the device is appropriatelyinstalled such that the pointer of the vial 210 aligns with theappropriate directional differential pressure markings resulting in theconduit having an angle of inclination that allows the bubble pointer212 to remain steady at the middle of the vial between the boundarylines 213. Hence, after appropriate installation, a directionaldifferential pressure in the direction from room 10 to room 20, of 0.02inches of H₂O or greater will generate enough air flow through theconduit to cause the ball to move from room 10 (lower end) to room 20(higher end).

If it is further desired that the device provide indication to anobserver of whether a directional different differential pressurebetween rooms is present, then the pivot can be appropriately adjustedso that the vial points to the appropriate one of the two similarmarkings which correspond to the desired pressure, of which theappropriate mark of the two is determined by adjusting the conduitincline with the low end in the desired higher pressure room and thehigh end in the desired lower pressure room so that the bubble 212reaches an equilibrium state in the middle of the vial e.g., betweenboundary lines 213.

For example, a change in the desired pressure difference between thespaces from 0.2 inches of H₂O to 0.03 inches of H₂O with the samedesired direction of air flow may involve a simple adjustment of thewing nut so that the vial 210 points to the closer marking thatreferences 0.03 inches of H₂O, which would involve positioning theconduit at a steeper angle of incline to put the bubble 212 in betweenthe boundary lines 213. Once the differential pressure set pointindicator is appropriately adjusted and the angle of inclination of theconduit is set within the wall such that the bubble pointer 212 remainssteady at the middle of the vial, the device is now ready to provide anaccurate indication of whether the desired direction of air anddirectional threshold differential pressure between rooms is actuallypresent.

FIG. 7 shows a device that includes a bubble differential pressure setpoint indicator. In this embodiment, the differential pressure set pointindicator 200 is attached to the conduit, via an appropriate base plate214, and includes a vial 210 that contains liquid and an associatedbubble pointer 212. Due to the geometry of the vial and gravity actingon the liquid within the vial, the bubble moves to the highest possiblepoint within the vial. Here, the vial 210 exhibits a geometry (e.g.,curvature) that allows for the bubble to provide differential pressureset point information at multiple regions along the vial. For instance,when the conduit is perfectly level, the bubble moves toward a positionwhere the vial and base plate correlate to being level. However, whenthe conduit is tilted at an angle, the position of the bubble relativeto the vial will change, so as to provide an indication that the conduitis set at a different angle of incline.

Accordingly, appropriate markings 220 are provided adjacent to the vialso that appropriate differential pressure set point information can beprovided to an observer (e.g., someone who is adjusting the tilt of theconduit) when the conduit is angled in a manner that brings the bubbleinto steady alignment near particular marking(s). Since the differentialpressure set point indicator can sense both directions of the conduitincline, there are two similar symmetric markings for each desiredthreshold differential pressure set point. Here, the markings 220 referto the threshold differential pressure between rooms required togenerate enough air flow through the conduit to move the ball from thelower end of the conduit to the higher end. That is, the conduit 110 maybe tilted so that the bubble pointer 212 aligns with the appropriate oneof the two similar markings which correspond to the desired pressure, ofwhich the appropriate mark of the two is determined by adjusting theconduit incline with the low end in the desired higher pressure room andthe high end in the desired lower pressure room so that the bubble 212remains in steady alignment and pointing to the desired marking thatindicates a particular value of the directional pressure differential.When the conduit is installed at the angle that corresponds to thatparticular value of pressure differential, movement of the ball 120 to ahigher region of the conduit may provide assurance to an observer thatthe directional differential pressure indicated by the bubble 212, at aminimum, actually exists between the separate spaces.

FIGS. 8-9 show devices that include ball-type differential pressure setpoint indicators where the differential pressure set point indicator 200includes a vial 210 with a ball pointer 212. The vial 210 is filled witha fluid (e.g., gas, liquid) and the ball pointer moves to the lowestpoint within the vial by force of gravity. The vial 210 may exhibit acurvature that permits the ball to provide information regarding theangle of incline of the conduit when the ball 212 remains in steadyalignment at various regions along the vial. For instance, when theconduit is perfectly level, the ball pointer 212 moves toward the middleof the vial. Though, when the conduit is tilted at an angle, the ballpointer 212 may still remain in steady alignment with a region of thevial that is offset from the middle of the vial.

Markings 220 are provided adjacent to the vial so that appropriateinformation can be provided when the conduit is tilted such that theball pointer 212 steadily aligns with a particular set of the markings.The markings 220 refer to the threshold differential pressure set pointbetween rooms required to create a sufficient degree of air flow thatmoves the ball 120 within the lumen of the conduit 110 from the lowerend of the conduit to the higher end. That is, the conduit 110 may betilted so that the ball pointer 212 aligns with markings that indicate aparticular value of directional pressure differential. When the conduitis installed at the angle that corresponds to that particular value ofdirectional pressure differential, movement of the ball 120 within thelumen from the lower end of the conduit to the higher end of the conduitmay provide assurance to an observer that the directional differentialpressure indicated by the ball pointer 212, at a minimum, actuallyexists between the rooms.

FIGS. 8 and 9 are various embodiments of ball-type differential pressureset point indicators 200 where the shape of the vial differs. Dependingon how the vial of a ball-type differential pressure set point indicatoris shaped, the markings 220 which relate the angle of incline of theconduit to the threshold pressure differential(s) between rooms will becalibrated and appropriately positioned.

The ball-type differential pressure set point indicator of FIG. 8provides for different threshold differential pressure set points. Sincethe differential pressure set point indicator can sense both directionsof the conduit incline, there are two similar symmetric markings foreach desired threshold differential pressure set point. The ball-typedifferential pressure set point indicator of FIG. 9 provides forthreshold differential pressure information for tilt of the conduit inonly one direction. and so the markings are uni-directional rather thanbi-directional as in FIGS. 5-8. In some embodiments, the ball-typedifferential pressure set point indicator of FIG. 9 as compared to thosein FIGS. 5-8, provides for a finer degree of set point adjustment forindicating whether the threshold differential pressure between rooms ispresent.

In the embodiment of FIG. 10, the device 10 includes a differentialpressure set point indicator 200 having a weighted pointer 210. Asshown, the differential pressure set point indicator 200 is rigidlysecured to the outer surface of the conduit 10 via base plate 214. Thedifferential pressure set point indicator 200 includes a tip pointer 212that is pivotally connected to the base plate 214. A weight 218 isprovided at an end opposite the tip pointer below the pivot point 216.When the conduit 110 is placed within a wall at an angle of inclinationwith respect to the horizontal, the tip pointer 212 will vary in itsposition and pivot to reflect the degree to which the conduit is tiltedwith respect to the horizontal.

The tip pointer is further adapted to rotate about the pivot point so asto point to the bi-directional reference markings 220, which arecalibrated to match the angle of incline with the threshold differentialpressure between opposite ends of the conduit 10 at which the ball 120will be urged against the force of gravity to move from the lower endtoward the opposite higher end of the conduit. As such, depending on theangle of incline of the conduit, the tip pointer will come into steadyalignment with reference markings 220 that are calibrated to representminimum differential pressures required to move and maintain the ball120 at a desired position within the conduit, for instance, at thehighest point.

FIG. 11 shows a device 10 that includes a pendulum differential pressureset point indicator 200. The differential pressure set point indicator200 is rigidly secured to the outer surface of the conduit 10 via baseplate 214. The differential pressure set point indicator 200 includes apendulum pointer 212 that is pivotally connected to the base plate 214at a point 216. Here, the pendulum pointer 212 extends downwardly androtates about the pivot point 216 so as to point to the bi-directionalreference markings 220 which are calibrated similarly to that describedabove regarding FIG. 10.

Thus, given a desired minimum differential pressure between enclosedspaces that are separated by a wall through which the conduit extends,appropriately calibrated differential pressure set point indicators withaccurate markings may allow the angle of inclination of the conduitaccording to the present disclosure to be easily adjusted to suit thedesired directional pressure differential. That is, the conduit of adevice installed into a wall separating two enclosed spaces may beoriented at a particular angle that corresponds to a thresholddifferential pressure between the separate spaces sufficient to cause aball, or other movable element, disposed within the conduit to move fromthe lower end to the higher end of the conduit. When it is desired forthat threshold differential pressure between the separate enclosedspaces to be altered, the differential pressure set point indicator,with appropriately calibrated reference markings, may be used as an easyreference to determine what the adjusted angle of the conduit should beto correspond to the new threshold pressure differential.

Such an adjustment of the angle of the conduit may be a relativelysimple procedure. For instance, in an embodiment described, fastenersattaching respective outer wall flanges 160 to inner wall flanges 150 ofthe device may be loosened and the outer wall flanges, which providesupport for the conduit, may be shifted vertically with respect to theinner wall flanges so as to suitably alter the angle of incline of theconduit. An appropriately calibrated differential pressure set pointindicator may be used as a reference to determine what angle of inclineto which the conduit should be set so as to correspond to the desiredthreshold differential pressure between opposite ends of the conduit.Once the conduit is oriented in accordance with the appropriate angle ofincline, the fasteners of respective outer wall flanges are thentightened to set the conduit firmly in place. Respective gaskets securedto the outer wall flanges may assist in holding the conduit securely atthe desired orientation.

Suitable adjustments of the angle of incline of the conduit may beperformed manually or automatically. For example, an operator may usethe above procedure to adjust the angle of incline of the conduitmanually.

Or, the device may be set up in accordance with an automated system thatis configured to adjust orientation of the conduit automaticallydepending on the desired level of differential pressure between spaceson opposite sides of the wall. In some embodiments, the device may beconfigured with a control system that automatically adjusts the angle ofincline of the conduit according to input provided by a user, or relatedcomputer system, of a desired differential pressure to be establishedbetween neighboring spaces. For example, a user may simply input theminimum differential pressure that is required between two rooms into auser interface and the system may automatically, without further userinteraction, adjust the angle of incline of the conduit to correspond tothe desired minimum differential pressure between rooms. In some cases,the control system may refer to the differential pressure set pointindicator by any suitable detection method, to determine the appropriateangle of incline of the conduit.

As discussed, physical features other than the incline of the conduitmay provide an indication of whether the directional differentialpressure between spaces meets a certain threshold.

For instance, the type of ball placed within the lumen of the conduitmay be chosen based on particular characteristics, such as weight orsurface finish of the ball. That is, a greater differential pressurewill be required to move a heavier ball from a lower region of theconduit to a higher region of the conduit. Conversely, if the ball islighter, a smaller differential pressure will be required to move theball toward the higher end of the conduit. Alternatively, a ball havinga rough surface finish may require a greater degree of air flow providedthrough differential pressure to move the ball toward the higher end ofthe conduit. Accordingly, different balls, or movable elements, may bemarked according to the range of differential pressure that thedetector, incorporating the particular ball(s), may indicate.

Alternatively, the type of stops at the ends of the conduit may bechosen according to the particular range of directional differentialpressure(s) to be detected. For example, for a given ball within theconduit, an end stop having a small orifice that limits the rate of airflow through the conduit may be used as an indicator for thedifferential pressure between the spaces. That is, where end stops of adetector have relatively small openings such that the rate of air flowthrough the openings is limited, a greater differential pressure will berequired to move a ball from a lower region of the conduit to a higherregion of the conduit. Conversely, if the openings are wider, allowing agreater flow rate of air through the conduit, a smaller differentialpressure may be required to move the movable element toward the higherend of the conduit. As a result, different end stops having differentorifice sizes may be marked according to the range of differentialpressure that the detector incorporating the particular end stop(s), mayindicate.

Thus, different components of the differential pressure detector may bemarked so as to provide an indication of the minimum differentialpressure threshold that would cause the movable element to move from alower end region toward a higher opposite end region of the conduit.Markings of the ball, conduit, end stops of the conduit, etc. may referto actual units of pressure indicating the directional thresholdpressure differential set point between rooms; such markings may bealphanumeric values to which a correlating table may be referred;alternatively, the markings may provide an actual property (e.g., ballweight, end stop orifice size, conduit curvature, conduit/ball surfacefinish, etc.) to which a correlating table may be referred, to determinethe corresponding directional threshold differential pressure set point.

A differential pressure set point indicator may be secured to anyportion of a device using any suitable manner. In some embodiments,differential pressure set point indicators are secured to a device(e.g., on the outer surface of the conduit) by an appropriate adhesiveor fastener. Or, as discussed below, an appropriate holder may be usedto mount the differential pressure set point indicator.

FIGS. 12 and 13 show an embodiment of a holder 300 for mounting thedifferential pressure set point indicator 200 on to the conduit 110. Theholder 300 includes a plate 310 to which a surface of a differentialpressure set point indicator may be attached. The holder 300 furtherincludes an elastically deformable spring clip 320 that wraps around theexterior of the conduit 110. In some embodiments, the spring clip 320has an opening 330 with ends that may be spread apart so that theconduit 110 may be suitably secured within the clip 320. As analternative, a split ring divided at one or more locations along thering, capable of fastening tight about the perimeter of the conduit maybe used to mount the differential pressure set point indicator.

In another aspect of the present disclosure, it may be desirable fornoise to be attenuated upon impact of the ball, or other movableelement, against either end stop that is useful for keeping the movableelement contained within the conduit. For instance, the ball and endstops of the device may be made of materials that produce a noticeablesound when the ball drops on to an end stop at the lower position orwhen the ball is pushed up against the end stop at the higher position.For example, a ping pong ball makes a distinct noise upon impact with arelatively rigid surface. In some cases, such a sound may be irritatingto people that may be located within either of the rooms that share thedevice. Thus, a sound attenuator or device may be included forsubstantially reducing noise when the ball moves from one end of theconduit to the opposite end and is subject to impact.

The sound attenuator may include any suitable material or combination ofmaterials. In some embodiments, the sound attenuator may include arelatively soft energy absorbing material, such as an elastomer, rubber,neoprene, silicone, plastic, polymer, foam, fibrous material, paper,tissue, netting, etc. In some embodiments, the sound attenuator mayexhibit a geometry that cushions the impact of the movable element on astop.

In some embodiments, a sound attenuator separate from the end stops isfitted with the end stop(s) of the conduit, as shown by way of example,in FIGS. 14-16 and 18A-18B. In other embodiments, the end stop(s)include an energy absorbing material which is sound attenuating and,hence, comprise the sound attenuator, for example, shown in FIG. 17.

FIGS. 14-15 show conduit 110 with an end stop 130 that forms a suitablefit (e.g., interference fit, snap fit) over an edge 112 of the conduit.Positioned between the edge 112 of the conduit and the end stop 130 is asound attenuator 140. In this embodiment, the ball 120 is a ping pongball and the end stop 130 is made of a hard plastic. Thus, withoutappropriate placement of the sound attenuator 140 between the conduitand the end stop, when the ball impacts against the end stop 130, anabrupt sound is produced which can be easily heard by a person locatedin the room where the impact occurs, and possibly in an adjacent roomwhere the other open end of the conduit resides. When the soundattenuator 140 is appropriately placed between the conduit and the endstop, impact of the ball against the sound attenuator 140 will produce amuch softer sound which is not as readily noticeable as compared withthe sound produced when the energy absorbing material is not present.

FIG. 16 depicts another embodiment of an end stop 130 associated with asound attenuator 140. Here, the sound attenuator 140 is attached (e.g.,adhered) to the inside surface of the end stop. The sound attenuator ismade of a material that is shaped in a geometry that absorbs impactenergy. Accordingly, when the ball impacts the sound attenuator 140, arelatively soft sound is produced as compared to instances where theenergy absorbing material in an energy absorbing geometry is notpresent.

As shown in FIGS. 14-16, the center axis of the opening of the soundattenuator 140 and the opening of the end stop 130 is offset from thecenter axis of the conduit, as depicted by the offset axes in eachfigure, yet is substantially aligned with the center axis along whichthe ball moves. Such alignment of the opening of the sound attenuatorwith the center of the ball is more effective for lessening the amountof sound generated upon impact at the end(s) of the conduit than wouldotherwise be the case without the alignment. Additionally, alignment ofthe opening of the end stop is also effective for directing air flowgenerated by the differential pressure toward the ball, rather thanallowing leakage of air flow around the ball, which could potentiallygive rise to inaccuracies in overall differential pressure indication bythe device. This alignment also may contribute to closing off the endstop or sound attenuator hole with the ball (e.g., forming a seal) andlimiting the transfer of air between rooms whenever the ball abuts theend stop or sound attenuator.

In some embodiments, the end stop itself is sound attenuating. As shownin FIG. 17, the end stop 130 includes an energy absorbing material. Insome embodiments, the end stop may exhibit a geometry similar to adiaphragm. As a result, a softer sound is produced when the ball impactsthe sound attenuating end stop as compared to an arrangement where theend stop was made of a relatively hard plastic.

FIG. 18A shows a device where a sound attenuator 140 (e.g., grommet) isfitted at the opening of the end stop 130. The sound attenuator mayattenuate sound that would otherwise be produced upon impact of the ballagainst the end stop of the conduit. In some embodiments, the soundattenuator is flexible so as to be removable from the opening of the endstop and subsequently replaced. In some embodiments, as shown in FIG.18B, the sound attenuator includes a flexible flap 142 surrounding aspace 144 that includes air and/or a soft material that absorbs theimpact of the ball. In other embodiments, the sound attenuator isintegrally formed with or permanently attached to the end stop.

FIG. 19 shows a device 100 in an installed configuration where theconduit is positioned at an angle with respect to the horizontal. Theball 120 rests against a replaceable sound attenuator 140, provided as agrommet which is, in turn, coupled to the end stop 130. The devicefurther includes protective coverings 400 surrounding each end of theconduit. The protective coverings 400 include openings 402 through whichfluid (e.g., air, gas) may flow from one room 10, through the conduit,and to the room 20 on the other side of the wall. The protectivecoverings 400 are shown in this embodiment to fit over the wall flange160 and the associated sealing material 162 in a secured manner, withthe edge of the coverings being in contact with the wall flange 150.

Protective coverings may be useful to shield the openings of theconduit, or the ball itself, from contamination or sudden rushes of airthat may affect positioning of the ball within the conduit (e.g., a rushof air that occurs when a door between rooms is opened, equalizing thepressure difference between rooms, or when a window is opened). Suchcoverings also may discourage people from playing with orinappropriately manipulating various parts of the device, which couldlead to damage to the device. For instance, absent the protectivecoverings, a person might be more likely to pull the end stop off of aconduit or inappropriately grasp the conduit as compared to if the endsare surrounding by the protective coverings. Thus, protective coveringsmay provide shielding for components of the device as well as deterpeople from potentially rendering the device non-functional.

To allow observers to view whether the ball is present at a particularend or other region of the conduit, protective coverings may betransparent, or substantially see-through.

FIG. 20 shows an exploded view of the device 100. As shown, theprotective covering 400 fits over the outer wall flange 160 and sealingmaterial 162. The outer wall flange 160 and outer sealing material 162are attached to an inner wall flange 150 via a suitable set offasteners. As discussed previously, the vertical position of a fastenerfor the outer wall flange 160 may be adjustable to suit the desiredangle of incline of the conduit 110. The inner wall flange 150, in turn,is attached to the inner sealing material 152 and the exterior surfaceof the wall (not shown in this figure) via another set of fasteners.

Referring to the conduit 110, the differential pressure set pointindicator 200 is attached to the exterior surface of the conduit. Theball 120 is disposed within the lumen of the conduit and the ends of theconduit are fitted with end stops 130 that prevent the ball from exitingthe conduit while, at the same time, having openings 132 on oppositeends that allow fluid to flow through the length of the conduit. Soundattenuating grommets 140 are placed within respective openings 132 ofthe end stops so that the ball does not make a substantially noticeablenoise upon impact with the end of the conduit.

In some embodiments, the sealing material 162 has an opening that has adiameter slightly smaller than the outer diameter of the conduit.Accordingly, the sealing material 162 may form a snug seal with theexterior surface of the conduit, preventing fluid from flowing throughthe opening of the wall flange 160, except through the lumen of theconduit. The diameter of the sealing material 162 is also slightlysmaller than the opening diameter of the wall flange 160 so as toaccommodate various orientations of the angled conduit within theopening of the wall flange 160.

As shown in FIG. 21, when the device is installed, the sealing material162 is in contact with the exterior surface of the conduit so as to forma seal between the surface of the wall (via the wall flanges) and theconduit. The opening of the wall flange 160 may also provide verticaltolerance for the position of the conduit to be adjusted (e.g.,adjusting the angle of inclination of the conduit).

The sealing material may be a gasket that is flexibly deformable. Such acharacteristic allows for the sealing material to accommodateadjustments in position of the conduit, while also maintaining the sealbetween the surface of the wall and the conduit. For example, as shownin FIG. 22, while the conduit may be positioned at a particular angle ofinclination, the seal remains unbroken. Further, the sealing material162 may be composed of a composition that also provides an appropriatedegree of support for the conduit while placed in the angled position.

The sealing material may comprise any suitable composition that isflexible, yet is appropriate for maintaining a seal. In someembodiments, the sealing material includes at least one of an elastomer,rubber, silicone, any other suitable composition and/or combinationsthereof.

While FIG. 22 shows how the sealing material distorts upon adjustment ofthe conduit into an angled orientation, the sealing material 162 notonly maintains the seal so as to prevent fluid flow from one side of thewall to the other over the exterior of the conduit, but also providessupport for the conduit in the angled orientation. That is, the sealingmaterial 162 may function as a gasket that substantially holds theconduit at the angled orientation. Accordingly, the sealing materialmitigates the occurrence of creep of the conduit from its set angledorientation, reducing potential inaccuracies in the overallindication(s) of differential pressure between rooms within whichopposite ends of the conduit are present.

In some embodiments, the device includes features that are adjustable inlength so as to accommodate installation of the device into differentwalls of varying thickness.

The embodiment illustrated in FIGS. 23-24 includes the device installedwith telescoping wall cavity barriers 300, 310. Here, the wall flanges150 and associated sealing materials 152 are attached to respective wallcavity barriers 300, 310, which are, in turn, attached to the exteriorsurfaces of the walls 52, 54. As shown in FIG. 23, when installed, thewall cavity barriers 300, 310 define a space within which the conduit110 is housed, providing an additional degree of protection for theconduit within the wall. In some embodiments, wall cavity barriersprovide protection for the conduit from any contaminants within the wallcavity 50 outside the lumen of the wall tubes 304, 305 from transmissioninto either of the rooms 10, 20 or conversely, any contaminants fromeither room 10, 20 from entering into the wall cavity outside the lumenof the wall tubes 304, 305.

As depicted in FIG. 24, the wall cavity barriers 300, 310 may includerespective wall plates 302, 312, wall tubes 304, 314 and sealingmaterials 306, 316. The wall plates 302, 312 provide for attachment ofthe device to the wall during installation. That is, the wall plates maybe attached (e.g., via fasteners, adhesives, etc.) on opposite sides ofthe wall to surfaces 52, 54 so that the wall tubes 304, 314 may extendinto the wall and provide protection and support for the angled conduit.Sealing materials 306, 316 may protect transmission of air between rooms10, 20 and the wall cavity 50.

The wall tubes 304, 314 operatively engage with one another, as shown inFIG. 23, so as to provide a housing for the conduit. For example, thewall tubes may be telescoping or otherwise slidable with respect to oneanother so that the wall cavity barrier may be appropriately installedin walls having different thicknesses. In some embodiments, the walltubes may include features, such as spring-loaded protrusions along thelength of one tube and corresponding holes along the length of anothertube that allow the overall length housed by the wall tubes to befixedly adjustable. Or, the wall tubes may include appropriateinterference/snap fit features that provide length adjustability of thetubes with respect to one another. Alternatively, the wall tubes may beremovably attached to each other via a suitable fastener and/or adhesivematerial. Telescoping tube arrangements may be of a sufficient interfacefit so as to prevent transmission of contaminated or unwanted airbetween the wall cavity 50 and the lumen of the wall tubes 304, 314.

As shown in FIGS. 23-24, the sealing materials 306, 316 may haveopenings for respective wall tubes 304, 314 so that a seal is formedbetween the exterior surfaces of the wall 52, 54 and the wall plates302, 312.

In some embodiments, the conduit itself may be adjustable in length.FIGS. 25-26 depict a telescoping conduit. In this embodiment, theconduit includes a first portion 116 and a second portion 118 that areoperatively engaged with one another so as to provide for lengthadjustability of the conduit. For instance, the first and secondportions of the conduit are configured to be telescoping or otherwiseslidable with respect to one another. As a result, the device may beinstalled into different walls having varying thickness.

Similar to the wall tubes discussed above, the first and second portionsof the conduit may include features that allow the length of the conduitto be appropriately adjusted. For example, such portions may includespring-loaded protrusions along the length of one portion andcorresponding holes along the length of the other portion so that theoverall length of the conduit is fixedly adjustable. Or, the conduitportions may have appropriate interference/snap fit features thatprovide length adjustability of the conduit. In some embodiments, therespective portions of the conduit may be removably attached to eachother via a suitable fastener and/or adhesive material.

Having thus described several aspects of at least one embodiment of thisinvention, it is to be appreciated various alterations, modifications,and improvements will readily occur to those skilled in the art. Suchalterations, modification, and improvements are intended to be part ofthis disclosure, and are intended to be within the spirit and scope ofthe invention. Accordingly, the foregoing description and drawings areby way of example only.

What is claimed is:
 1. A device for detecting a directional differentialpressure between two spaces, comprising: an elongated conduit arrangedto be coupled with a wall separating the two spaces, the conduit havingopenings at opposite ends that permit fluid flow between the two spacesthrough the conduit, wherein the conduit comprises a first portion and asecond portion operatively engaged with one another to provide lengthadjustability of the conduit; and at least one movable element disposedwithin the conduit adapted to be moved from one region of the conduittoward an opposing region in response to the differential pressure. 2.The device of claim 1, wherein the conduit is configured to accommodatevariations in wall thickness.
 3. The device of claim 1, wherein thefirst and second portions of the conduit are configured to betelescoping with respect to one another.
 4. The device of claim 1,further comprising a first wall cavity barrier and a second wall cavitybarrier each adapted to be placed on opposite sides of the wall andadapted to prevent fluid communication between the wall cavity and thesaid two spaces.
 5. The device of claim 4, wherein a first portion ofthe first wall cavity barrier and a second portion of the second wallcavity barrier are operatively engaged with one another to accommodatevariations in wall thickness.
 6. The device of claim 5, wherein thefirst portion of the first wall cavity barrier and the second portion ofthe second wall cavity barrier are configured to be telescoping withrespect to one another.
 7. A device for detecting a directionaldifferential pressure between two spaces, comprising: an elongatedconduit arranged to be coupled with a wall separating the two spaces,the conduit having openings at opposite conduit ends that permit fluidflow between the two spaces through the conduit; at least one movableelement disposed within the conduit adapted to be moved from one regionof the conduit toward an opposing region in response to the differentialpressure; and a sound attenuator adapted to limit noise upon the atleast one movable element reaching a conduit end, wherein the soundattenuator is formed from an energy absorbing material; wherein thesound attenuator is formed of at least one of an elastomer, rubber,neoprene, silicone, foam, fibrous material, paper, tissue, and netting.8. The device of claim 7, wherein an end stop of the conduit and the atleast one movable element are configured to be in contact with eachother when the one movable element is positioned at one end of theconduit.
 9. The device of claim 7, further comprising an end stopconfigured for placement at the conduit end, the energy absorbingmaterial coupled with the end stop.
 10. The device of claim 7, whereinthe sound attenuator includes an elastomeric grommet that is configuredto engage with an inner surface of an opening of the conduit.
 11. Adevice for detecting a directional differential pressure between twospaces, comprising: an elongated conduit arranged to be coupled with awall separating the two spaces, the conduit having openings at oppositeends that permit fluid flow between the two spaces through the conduit,and the conduit having an adjustable angle of inclination relative to ahorizontal plane; a sealing material in contact with an exterior surfaceof the conduit and adapted to support the conduit in an installedorientation, wherein the sealing material is configured to flex inresponse to a change in the angle of inclination of the conduit; and atleast one movable element disposed within the conduit adapted to bemoved from one region of the conduit toward an opposing region inresponse to the differential pressure.
 12. The device of claim 11,further comprising wall plates coupled to the conduit and configured tomaintain the conduit at an angle of inclination with respect to ahorizontal plane.
 13. The device of claim 11, wherein an openingdiameter of the sealing material is less than an opening diameter of atleast one wall plate.
 14. The device of claim 11, wherein an openingdiameter of the sealing material is less than an outer diameter of theconduit and the sealing material is flexibly deformable with respect tothe conduit.
 15. A device for detecting directional differentialpressure between two spaces, comprising: an elongated conduit arrangedto be coupled with a wall separating a first space from a second space,the conduit having openings at opposite ends that permit fluid flowthrough the conduit from the first space to the second space, theconduit arranged to be inclined with respect to a horizontal referenceplane such that a first region of the conduit associated with the firstspace is vertically lower than a second, vertically higher region of theconduit that is associated with the second space; at least one movableelement disposed within the conduit; and a differential set pointindicator configured to provide a set point indication of a thresholddifferential pressure between the first and second spaces that issufficient to cause the at least one movable element to move from thefirst, vertically lower region of the conduit to the second, verticallyhigher region in response to a differential pressure between the firstand second spaces; wherein the differential set point indicator includesa pointer which moves in response to a change in an angle of inclinationof the conduit with respect to the horizontal reference plane, and themovement of the pointer is due to a weight of the pointer.
 16. Thedevice of claim 15, wherein the conduit includes a marking thatindicates the threshold differential pressure between the first andsecond spaces that is sufficient to cause the at least one movableelement, when disposed within the conduit, to move from the first,vertically lower region of the conduit to the second, vertically higherregion in response to a differential pressure between the first andsecond spaces.
 17. The device of claim 15, wherein at least one of theopenings of the conduit is offset from a center axis of the conduit andaligned with a center axis along which the at least one movable elementis adapted to move in response to a differential pressure between thefirst and second spaces.
 18. A device for detecting a directionaldifferential pressure between two spaces, comprising: an elongatedconduit arranged to be coupled with a wall separating the two spaces,the conduit having openings at first and second opposite ends thatpermit fluid flow between the two spaces through the conduit; an endstop positioned at the first end of the conduit; a movable elementdisposed within the conduit adapted to be moved from one region of theconduit toward an opposing region in response to the differentialpressure; and a sound attenuator adapted to reduce noise upon the atleast one movable element reaching the first end of the conduit, whereinthe sound attenuator is positioned between the movable element and theend stop.
 19. The device of claim 18, wherein the sound attenuator isformed of silicone.
 20. The device of claim 18, wherein the soundattenuator is mounted to a perimeter of the opening that is at the firstend of the conduit.
 21. The device of claim 18, wherein the soundattenuator is positioned between the end stop and an edge of the firstend of the conduit.